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nfsd: Revert "nfsd: release svc_expkey/svc_export with rcu_work"

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This reverts commit f8c989a0c8.

Before this commit, svc_export_put or expkey_put will call path_put with
sync mode. After this commit, path_put will be called with async mode.
And this can lead the unexpected results show as follow.

mkfs.xfs -f /dev/sda
echo "/ *(rw,no_root_squash,fsid=0)" > /etc/exports
echo "/mnt *(rw,no_root_squash,fsid=1)" >> /etc/exports
exportfs -ra
service nfs-server start
mount -t nfs -o vers=4.0 127.0.0.1:/mnt /mnt1
mount /dev/sda /mnt/sda
touch /mnt1/sda/file
exportfs -r
umount /mnt/sda # failed unexcepted

The touch will finally call nfsd_cross_mnt, add refcount to mount, and
then add cache_head. Before this commit, exportfs -r will call
cache_flush to cleanup all cache_head, and path_put in
svc_export_put/expkey_put will be finished with sync mode. So, the
latter umount will always success. However, after this commit, path_put
will be called with async mode, the latter umount may failed, and if
we add some delay, umount will success too. Personally I think this bug
and should be fixed. We first revert before bugfix patch, and then fix
the original bug with a different way.

Fixes: f8c989a0c8 ("nfsd: release svc_expkey/svc_export with rcu_work")
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Yang Erkun 2024-12-16 22:21:52 +08:00 committed by Chuck Lever
parent 583772eec7
commit 69d803c40e
2 changed files with 8 additions and 27 deletions
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31
fs/nfsd/export.c
View File

@ -40,24 +40,15 @@
#define EXPKEY_HASHMAX (1 << EXPKEY_HASHBITS)
#define EXPKEY_HASHMASK (EXPKEY_HASHMAX -1)
static void expkey_put_work(struct work_struct *work)
static void expkey_put(struct kref *ref)
{
struct svc_expkey *key =
container_of(to_rcu_work(work), struct svc_expkey, ek_rcu_work);
struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
if (test_bit(CACHE_VALID, &key->h.flags) &&
!test_bit(CACHE_NEGATIVE, &key->h.flags))
path_put(&key->ek_path);
auth_domain_put(key->ek_client);
kfree(key);
}
static void expkey_put(struct kref *ref)
{
struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
INIT_RCU_WORK(&key->ek_rcu_work, expkey_put_work);
queue_rcu_work(system_wq, &key->ek_rcu_work);
kfree_rcu(key, ek_rcu);
}
static int expkey_upcall(struct cache_detail *cd, struct cache_head *h)
@ -364,26 +355,16 @@ static void export_stats_destroy(struct export_stats *stats)
EXP_STATS_COUNTERS_NUM);
}
static void svc_export_put_work(struct work_struct *work)
static void svc_export_put(struct kref *ref)
{
struct svc_export *exp =
container_of(to_rcu_work(work), struct svc_export, ex_rcu_work);
struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
path_put(&exp->ex_path);
auth_domain_put(exp->ex_client);
nfsd4_fslocs_free(&exp->ex_fslocs);
export_stats_destroy(exp->ex_stats);
kfree(exp->ex_stats);
kfree(exp->ex_uuid);
kfree(exp);
}
static void svc_export_put(struct kref *ref)
{
struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
INIT_RCU_WORK(&exp->ex_rcu_work, svc_export_put_work);
queue_rcu_work(system_wq, &exp->ex_rcu_work);
kfree_rcu(exp, ex_rcu);
}
static int svc_export_upcall(struct cache_detail *cd, struct cache_head *h)

4
fs/nfsd/export.h
View File

@ -75,7 +75,7 @@ struct svc_export {
u32 ex_layout_types;
struct nfsd4_deviceid_map *ex_devid_map;
struct cache_detail *cd;
struct rcu_work ex_rcu_work;
struct rcu_head ex_rcu;
unsigned long ex_xprtsec_modes;
struct export_stats *ex_stats;
};
@ -92,7 +92,7 @@ struct svc_expkey {
u32 ek_fsid[6];
struct path ek_path;
struct rcu_work ek_rcu_work;
struct rcu_head ek_rcu;
};
#define EX_ISSYNC(exp) (!((exp)->ex_flags & NFSEXP_ASYNC))